Question: Complete the square to solve for $x$. $x^{2}+16x+55 = 0$
Explanation: Begin by moving the constant term to the right side of the equation. $x^2 + 16x = -55$ We complete the square by taking half of the coefficient of our $x$ term, squaring it, and adding it to both sides of the equation. Since the coefficient of our $x$ term is $16$ , half of it would be $8$ , and squaring it gives us ${64}$ $x^2 + 16x { + 64} = -55 { + 64}$ We can now rewrite the left side of the equation as a squared term. $( x + 8 )^2 = 9$ Take the square root of both sides. $x + 8 = \pm3$ Isolate $x$ to find the solution(s). $x = -8\pm3$ So the solutions are: $x = -5 \text{ or } x = -11$ We already found the completed square: $( x + 8 )^2 = 9$